Axial length decrease accompanying successful glaucoma filtration surgery.

OBJECTIVE: To evaluate change in axial length measurement after successful glaucoma filtering surgery.
DESIGN: Retrospective consecutive case series. PARTICIPANTS: Sixty-two patients with phakia who underwent primary trabeculectomy. INTERVENTION: The A-scan biometry of ocular axial length before and after trabeculectomy. MAIN OUTCOME MEASURES: Changes in ocular axial length measurement after successful trabeculectomy were analyzed.
RESULTS: The mean decrease in axial length measurement was 0.423 mm (range, -2.8 to +0.5 mm). Regression analysis yielded a statistically significant association between decrease in axial length measurement and age (P = 0.0001) and post-trabeculectomy intraocular pressure decrease greater than 30 mmHg (P = 0.01). Analysis of variance revealed a significant association between decrease in axial length measurement and use of antimetabolite (P = 0.005). Pseudophakic axial length measurements increased an average of 0.275 mm compared to the axial length after trabeculectomy and before cataract surgery.
CONCLUSIONS: Axial length measurement decreased in 32 of 62 eyes after successful initial trabeculectomy. A decrease in axial length measurement may have an influence on intraocular lens calculations. Therefore, the authors recommend that an axial length measurement be obtained on phakic eyes before an initial trabeculectomy to reduce the risk of an inaccurate intraocular lens power calculation based on post-trabeculectomy axial length measurements.